Dumb and Dumbler

[dreric]

So................ after a long hiatus from this project I'm back to working on the tandem builds, a Bluesmaster and a 102.

I have a challenge with the bluesmaster. Brought the voltage up on the variac, no tubes. At about 50volts the first two 470k bleeders resistors on the B2+ caps started to smoke.

Seems like a dead short somewhere but I can't seem to find one, suggestions?

Thanks

Eric

[dreric]

Not to be out done, when I brought the 102 up, no smoke but the relay transformer fried.

Suggestions

Thanks
Eric

[ToneMerc]

So................ after a long hiatus from this project I'm back to working on the tandem builds, a Bluesmaster and a 102.

I have a challenge with the bluesmaster. Brought the voltage up on the variac, no tubes. At about 50volts the first two 470k bleeders resistors on the B2+ caps started to smoke.

Seems like a dead short somewhere but I can't seem to find one, suggestions?

Thanks

Eric

That node has the choke out, screen supply and screen ground in that order. You don't by chance have the ground transposed at the pwr board do you?

TM

[ToneMerc]

Not to be out done, when I brought the 102 up, no smoke but the relay transformer fried.

Suggestions

Thanks
Eric

Looks like a FWB relay suppy right? Does the relay PT have a center tap connected or not?

TM

[markusw]

So................ after a long hiatus from this project I'm back to working on the tandem builds, a Bluesmaster and a 102.

I have a challenge with the bluesmaster. Brought the voltage up on the variac, no tubes. At about 50volts the first two 470k bleeders resistors on the B2+ caps started to smoke.

Seems like a dead short somewhere but I can't seem to find one, suggestions?

Thanks

Eric

Can't tell from the pictures for sure but two of the bleeder resistors look like 470R or 4k7 (image "current 002.jpg").
Can't see the colour codes on the smoked resistors, though.

Regards,

Markus

[Phazor]

Relay transformer fried.

I had a transformer like that and the output taps on the transformer actually touched the chassis under the transformer. I didn't notice this until I pulled the transformer out it had a dead output but got hot. I shimmed some fish paper insulator under transformer so the binding post could not touch the chassis.

Just a thought.

[Structo]

Can't tell from the pictures for sure but two of the bleeder resistors look like 470R or 4k7 (image "current 002.jpg").
Can't see the colour codes on the smoked resistors, though.

Regards,

Markus

Yes, should be Yellow, Violet, Yellow

470k 1w